Add MiddleClickDragScroll (#296)

* Add MiddleClickDragScroll

* Block mouse events while dragging

Source/MiddleClickDragScroll.spoon/init.lua

@@ -0,0 +1,261 @@
+--- === MiddleClickDragScroll ===
+---
+--- Allows scrolling by holding down the middle mouse button and dragging it, the same as it works on Windows.
+--- Especially useful to quickly scroll to the top or bottom of a page, if you don't have a Magic Mouse.
+---
+--- Note: Due to OS limitations, it always scrolls the window currently below the mouse, not the window below the position
+--- where the dragging started, like it works on Windows. You therefore need to take some care to stay inside the window.
+---
+--- == Usage ==
+---
+--- ```lua
+--- local MiddleClickDragScroll = hs.loadSpoon("MiddleClickDragScroll"):start()
+--- ```
+---
+--- You can temporarily stop the spoon by calling `MiddleClickDragScroll:stop()` and then restart it by calling `MiddleClickDragScroll:start()` again.
+---
+--- == Configuration ==
+---
+--- ```lua
+--- local MiddleClickDragScroll = hs.loadSpoon("MiddleClickDragScroll"):configure{
+---   excludedApps = {"Some App", "Other app"},         -- Don't activate scrolling in apps with these names
+---   excludedWindows = {"^Some Window Title$"},        -- Don't activate scrolling in windows with these names (supports regex, for exact match, use "^title$")
+---   excludedUrls = {"^https://geogebra.calculator$"}, -- Don't activate scrolling when the active window is on these URLs (supports regex, only works in Chrome and Safari, asks for extra permissions on first trigger)
+---   indicatorSize = 25,   -- Size of the scrolling indicator in pixels
+---   indicatorAttributes = -- Attributes of the scrolling indicator. Takes any specified on https://www.hammerspoon.org/docs/hs.canvas.html#attributes. Alternatively, you can pass a custom canvas, see the explenation below.
+---   {
+---     type = "circle",
+---     fillColor = { red = 0, green = 0, blue = 0, alpha = 0.3 },
+---     strokeColor = { red = 1, green = 1, blue = 1, alpha = 0.5 },
+---   },
+---   startDistance = 15,       -- Minimal distance to drag the mouse before scrolling is triggered.
+---   scrollMode = "pixel",     -- Whether the scroll speed is in "line"s or "pixel"s. Scrolling by lines has smooting in some applications
+---                             -- and therefore works with reduced frequency but it offers much less precise control.
+---   scrollFrequency = 0.01,   -- How often to trigger scrolling (in seconds)
+---   scrollAccelaration = 30,  -- How fast scrolling accelerates based on the mouse distance from the initial location. Larger is faster.
+---   scrollSpeedFn =           -- How scrolling accelerates based on the mouse distance from the initial location.
+---                             -- The default is dist^2 / scrollAcceleration^2. You can pass a custom function that recieves `self` as the first argument
+---                             -- and the absolute distance as the second and returns the resulting speed (in pixels or lines, depending on the scrollMode setting).
+---   function(self, x)
+---     return (x ^ 2) / (self.scrollAccelaration ^ 2)
+---   end
+--- }:start()
+--- ```
+---
+--- Unspecified keys are unchanged. You can call `configure` multiple times to dynamically change it but changing `indicatorAttributes` and `indicatorSize` only works when `MiddleClickDragScroll` is stopped.
+---
+--- Instead of `indicatorSize` and `indicatorAttributes`, you can also pass a custom canvas to `configure` or set it directly to have more control over the indicator style:
+---
+--- ```lua
+---   MiddleClickDragScroll.canvas = hs.canvas.new{ w = 25, h = 25}:insertElement{
+---     type = "circle",
+---     fillColor = { red = 0, green = 0, blue = 0, alpha = 0.3 },
+---     strokeColor = { red = 1, green = 1, blue = 1, alpha = 0.5 },
+---   }
+--- ```
+---
+--- For more details, see: https://www.hammerspoon.org/docs/hs.canvas.html
+---
+--- Download: [https://github.com/Hammerspoon/Spoons/raw/master/Spoons/MiddleClickDragScroll.spoon.zip](https://github.com/Hammerspoon/Spoons/raw/master/Spoons/MiddleClickDragScroll.spoon.zip)
+
+local MiddleClickDragScroll = {}
+
+MiddleClickDragScroll.author = "Benedikt Werner <[email protected]>"
+MiddleClickDragScroll.homepage = "https://github.com/benediktwerner/MiddleClickDragScroll.spoon"
+MiddleClickDragScroll.license = "MIT"
+MiddleClickDragScroll.name = "MiddleClickDragScroll"
+MiddleClickDragScroll.version = "1.0.0"
+MiddleClickDragScroll.spoon = hs.spoons.scriptPath()
+
+MiddleClickDragScroll.excludedApps = {}       -- Don't activate scrolling in apps with these names
+MiddleClickDragScroll.excludedWindows = {}    -- Don't activate scrolling in windows with these names (supports regex)
+MiddleClickDragScroll.excludedUrls = {}       -- Don't activate scrolling when the active window is on these URLs (supports regex, only works in Chrome and Safari, asks for extra permissions on first trigger)
+MiddleClickDragScroll.indicatorSize = 25      -- Size of the scrolling indicator in pixels
+MiddleClickDragScroll.indicatorAttributes =   -- Attributes of the scrolling indicator. Takes any specified on https://www.hammerspoon.org/docs/hs.canvas.html#attributes. Alternatively, you can pass a custom canvas.
+{
+  type = "circle",
+  fillColor = { red = 0, green = 0, blue = 0, alpha = 0.3 },
+  strokeColor = { red = 1, green = 1, blue = 1, alpha = 0.5 },
+}
+MiddleClickDragScroll.startDistance = 15      -- Minimal distance to drag the mouse before scrolling is triggered.
+MiddleClickDragScroll.scrollMode = "pixel"    -- Whether the scroll speed is in "line"s or "pixel"s. Scrolling by lines has smooting in some applications and therefore works with reduced frequency but it offers much less precise control.
+MiddleClickDragScroll.scrollFrequency = 0.01  -- How often to trigger scrolling (in seconds)
+MiddleClickDragScroll.scrollAccelaration = 30 -- How fast scrolling accelerates based on the mouse distance from the initial location. Larger is faster.
+MiddleClickDragScroll.scrollSpeedFn =         -- How scrolling accelerates based on the mouse distance from the initial location. The default is dist^2 / scrollAcceleration^2. You can pass a custom function that recieves `self` as the first argument and the absolute distance as the second and returns the resulting speed (in pixels or lines, depending on the scrollMode setting)
+function(self, x)
+  return (x ^ 2) / (self.scrollAccelaration ^ 2)
+end
+
+local function signum(n)
+  if n > 0 then return 1
+  elseif n < 0 then return -1
+  else return 0 end
+end
+
+local function getWindowUnderMouse()
+  -- Adapted from SkyRocket.spoon
+  -- Invoke `hs.application` because `hs.window.orderedWindows()` doesn't do it and breaks itself
+  local _ = hs.application
+
+  local mousePos = hs.geometry.new(hs.mouse.absolutePosition())
+  local screen = hs.mouse.getCurrentScreen()
+
+  return hs.fnutils.find(hs.window.orderedWindows(), function(w)
+    return screen == w:screen() and mousePos:inside(w:frame())
+  end)
+end
+
+function MiddleClickDragScroll:init()
+  self.position = nil
+  self.isScrolling = false
+  self.timer = nil
+
+  self.middleMouseDownEventTap = hs.eventtap.new({hs.eventtap.event.types.otherMouseDown}, self:handleMouseDown())
+  self.middleMouseDraggedEventTap = hs.eventtap.new({hs.eventtap.event.types.otherMouseDragged}, self:handleMouseDragged())
+  self.middleMouseUpEventTap = hs.eventtap.new({hs.eventtap.event.types.otherMouseUp}, self:handleMouseUp())
+end
+
+function MiddleClickDragScroll:handleMouseDown()
+  return function(event)
+    self.isScrolling = false
+    if self.timer ~= nil then
+      self.timer:stop()
+      self.timer = nil
+    end
+
+    if event:getProperty(hs.eventtap.event.properties.mouseEventButtonNumber) ~= 2 then
+      return
+    end
+
+    local window = getWindowUnderMouse()
+    if window == nil then return end
+
+    local appTitle = window:application():title()
+    if hs.fnutils.some(self.excludedApps, function(a) return a == appTitle end) then return end
+
+    local windowTitle = window:title()
+    if hs.fnutils.some(self.excludedWindows, function(w) return windowTitle:match(w) end) then return end
+
+    if appTitle == "Safari" and #self.excludedUrls > 0 then
+      local _, url = hs.osascript.applescript('tell application "Safari" to return URL of current tab of front window')
+      if hs.fnutils.some(self.excludedUrls, function(u) return url:match(u) end) then return end
+    end
+
+    if appTitle == "Google Chrome" and #self.excludedUrls > 0 then
+      local _, url = hs.osascript.applescript('tell application "Google Chrome" to return URL of active tab of front window')
+      if hs.fnutils.some(self.excludedUrls, function(u) return url:match(u) end) then return end
+    end
+
+    self.startPos = event:location()
+
+    return true
+  end
+end
+
+function MiddleClickDragScroll:handleMouseDragged()
+  return function(event)
+    if event:getProperty(hs.eventtap.event.properties.mouseEventButtonNumber) ~= 2 or self.startPos == nil then
+      return
+    end
+
+    local loc = event:location()
+    if loc == nil then
+      return true
+    end
+
+    self.currPos = loc
+
+    if self.isScrolling then
+      return true
+    end
+
+    if (loc.x - self.startPos.x) ^ 2 + (loc.y - self.startPos.y) ^ 2 > self.startDistance ^ 2 then
+      self.isScrolling = true
+      local frame = self.canvas:frame()
+      self.canvas:topLeft{ x = self.startPos.x - frame.w / 2, y = self.startPos.y - frame.h / 2 }:show()
+      self.timer = hs.timer.doEvery(self.scrollFrequency, function(t)
+        local xDiff = self.startPos.x - self.currPos.x
+        local yDiff = self.startPos.y - self.currPos.y
+        hs.eventtap.scrollWheel(
+          {
+            math.floor(self:scrollSpeedFn(xDiff)) * signum(xDiff),
+            math.floor(self:scrollSpeedFn(yDiff)) * signum(yDiff),
+          },
+          {},
+          self.scrollMode
+        )
+      end)
+    end
+
+    return true
+  end
+end
+
+function MiddleClickDragScroll:handleMouseUp()
+  return function(event)
+    if event:getProperty(hs.eventtap.event.properties.mouseEventButtonNumber) ~= 2 or self.startPos == nil then
+      return
+    end
+
+    if self.timer ~= nil then
+      self.timer:stop()
+      self.timer = nil
+    end
+
+    self.startPos = nil
+    self.canvas:hide()
+
+    if not self.isScrolling then
+      self.middleMouseDownEventTap:stop()
+      self.middleMouseUpEventTap:stop()
+      hs.eventtap.middleClick(event:location(), 1)
+      self.middleMouseUpEventTap:start()
+      self.middleMouseDownEventTap:start()
+    end
+
+    return true
+  end
+end
+
+function MiddleClickDragScroll:configure(options)
+  self.excludedApps = options.excludedApps or self.excludedApps 
+  self.excludedWindows = options.excludedWindows or self.excludedWindows 
+  self.excludedUrls = options.excludedUrls or self.excludedUrls 
+  self.startDistance = options.startDistance or self.startDistance 
+  self.scrollMode = options.scrollMode or self.scrollMode 
+  self.scrollFrequency = options.scrollFrequency or self.scrollFrequency 
+  self.scrollSpeed = options.scrollSpeed or self.scrollSpeed 
+  self.scrollSpeedFn = options.scrollSpeedFn or self.scrollSpeedFn 
+  self.canvas = options.canvas or self.canvas
+  self.indicatorSize = options.indicatorSize or self.indicatorSize
+  self.indicatorAttributes = options.indicatorAttributes or self.indicatorAttributes
+  if options.indicatorSize or options.indicatorAttributes then
+    self.canvas = nil
+  end
+  return self
+end
+
+function MiddleClickDragScroll:start()
+  if self.canvas == nil then
+    self.canvas = hs.canvas.new{ w = self.indicatorSize, h = self.indicatorSize }
+    self.canvas:insertElement(self.indicatorAttributes)
+  end
+
+  self.middleMouseDownEventTap:start()
+  self.middleMouseDraggedEventTap:start()
+  self.middleMouseUpEventTap:start()
+  return self
+end
+
+function MiddleClickDragScroll:stop()
+  self.middleMouseDownEventTap:stop()
+  self.middleMouseDraggedEventTap:stop()
+  self.middleMouseUpEventTap:stop()
+  return self
+end
+
+function MiddleClickDragScroll:isEnabled()
+  return self.middleMouseDownEventTap:isEnabled()
+end
+
+return MiddleClickDragScroll